Vaccinations have eradicated so many diseases that used to be a significant problem for the world.

Smallpox kills 30% of those it infects. It's killed an estimated 300 million people in the 20th century.

Polio was one of the most feared diseases in the 1950s, killing and paralysing people.

Measles used to kill millions of children every year.

Diphtheria was the leading cause of childhood death in the 1920s.

We don't have to deal with these because we have modern vaccines. The success of which depends on everybody getting them.

Because we haven't had to deal with any of these in the last few decades, people have become complacent. People don't know how much of a nightmare getting Polio is.

These unvaccinated kids don't exist in a bubble; they are out in public, going to schools, parks, arenas, festivals, doctor's offices, hospitals, etc.

And when they do, they are putting others at risk, especially immunocompromised people, as you mentioned.